Archived

Avalanche Forecast

Apr 6th, 2014–Apr 7th, 2014

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Forecast warm temperatures, high freezing levels, and sunny skies are expected to increase the avalanche danger.

Confidence

Good

Weather Forecast

Overnight and Monday: Freezing levels rising overnight to about 2200 metres. Light Westerly winds with mostly clear skies and no precipitation.Tuesday: Freezing levels continue to rise up to about 2600 metres. Southwest winds building to strong in the afternoon combined with moderate to heavy precipitation. Mostly sunny in the morning becoming cloudy in the afternoon.Wednesday: Freezing levels dropping down to 1500 metres as the cold front passes through the region. Sunny with cooler temperatures and light Northwest winds.

Avalanche Summary

Explosives control resulted in several avalanches up to size 2.0 in the Nelson area. Some loose wet slides up to size 1.5 were reported from solar aspects.

Snowpack Summary

The new snow increased the recent storm slab to 15-40 cm in depth. The new thin storm slab is sitting on a 2-5 cm melt-freeze crust that developed last week on all but shaded North aspects in the alpine. This crust has been reported to be "knife" resistance in some parts of the region and may have a layer of surface hoar below the new storm snow. There is now about 75 cm of well compacted snow above the March 10th melt-freeze crust. In some areas the March 10th crust is helping to bridge over the deeply buried late January/early February persistent weak layer. The Jan/Feb deep persistent weak layer continues to be a concern for very large destructive avalanches. Releases on this layer may be more likely during periods of strong solar radiation and/or prolonged warm temperatures at alpine elevations.

Avalanche Problems

Storm Slabs

Incremental loading has developed a storm slab that is between 15-40 cm thick. This storm slab continues to be triggered by heavy loads like explosives and cornice falls. Rising freezing levels may increase sensitivity to triggering.

Use ridges or ribs to avoid pockets of wind loaded snow.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Deep Persistent Slabs

The deeply buried weak layer of crusts and facets continues to be a concern for hard to predict very large avalanches. Warm temperatures, strong solar, or heavy loading from new snow or cornice falls are likely triggers.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6

Loose Wet

Forecast rising freezing levels and strong solar radiation may result in loose wet avalanches releasing from steep terrain on solar aspects.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3